Criteria for defining patient types that require the facilities and expertise of a specialized trauma center will be determined using the framework of Patient Management Categories (PMCs), a clinically-specific anatomical and pathological patient classification. This computerized classification will be used in conjunction with physiological measures from trauma registry data to define trauma patient types and to assess measures of severity and resource intensity. Trauma registry data from three major trauma center hospitals in Pennsylvania will be used in criterion development. The resultant criteria will be validated using patient data from at least three other trauma center hospitals in Pennsylvania. Extensive physician consultation will be used throughout. Consistent patient data will be collected prospectively from six test sites using software that will be designed and developed as part of this research. Trauma patient costs will be derived through a detailed cost-finding process in the six test sites and contrasted with DRG payments for trauma are in those institutions. Comparative analyses of the cost and effectiveness of trauma care provided at these hospitals will be performed. To the extent possible, criteria developed for defining levels of trauma care will be applied retrospectively to patient data available from hospitals in Pennsylvania and the state of Maryland. These data will be used to test and refine the criteria further and to develop an analytic model for evaluating regional patterns of trauma care.